Klein grew up in Monterey Park, California, the son of a Jewish aerospace engineer father and a stay at home mother.[9][10] When Klein was in the junior high school, his mother enrolled him in The Community School for the Performing Arts, an after-school music program sponsored by the University of Southern California.[1][3][9] Klein studied music composition and music theory through the program and began playing in rock bands.[9] By the time he was 17, Klein became interested in the technical challenges jazz music presented to him.[9][11]

In 1982, Klein began working as a bassist on Joni Mitchell'sWild Things Run Fast.[9][11] The two became romantically involved and married the same year.[11] It was during his marriage with Mitchell that Klein established himself as a music producer.[11]

Klein and Mitchell's marriage dissolved during 1994 while in the midst of making Mitchell's Turbulent Indigo album.[4][11] The two continued to work through their eventual divorce, and Turbulent Indigo won the 1995 Grammy for Best Pop Album.[8][11]

Klein has won four Grammys: Best Pop Album in 1996 for Joni Mitchell's Turbulent Indigo, Best Traditional Pop Vocal Album for Mitchell's Both Sides Now in 2001, Album of the Year and Best Contemporary Jazz Album for Herbie Hancock's album, River: The Joni Letters in 2008.[1][2][3][28][29]